12.5 Inch Telescope Mirror Blank

In stock
  • Schott BOROFLOAT® 33 borosilicate glass
  • Low thermal expansion
  • plano x plano, straight sides
  • virtually no bubbles
  • 1" thickness

A 12.5 inch aperture telescope is a great size for amateur telescope makers who have previous successful experience in mirror making. The first thing you will need to make is your primary. or objective, mirror. With this top quality mirror blank and the appropriate abrasives, polish, and pitch you will be able to make a telescope mirror to your own specifications that can potentially out-perform many mass produced telescopes.

Our 12.5 inch blanks are made from Schott BOROFLOAT® 33 borosilicate glass, the predecessor to Pyrex®, which is no longer made. The advantage to this glass is its low coefficient of thermal expansion which helps your mirror to stabilize quickly as temperature changes through a long night of astronomical discoveries.

More Information
Glass Type Supremax® 33 Borosilicate Glass
Diameter 12.500 in.
Thickness 1 in.
Coefficient of Thermal Expansion 3.25 x 10-6 K-1 (20-300°C / 68-572°F)
Density 2.2 g/cm2
Weight 22.25
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